SAN DIEGO (AP) — Morris Choo’s losing lottery ticket may have been the luckiest of his life.

Choo, 35, said he had been chatting with friends at a construction walkway but left to buy the ticket minutes before the block-long wooden structure collapsed Thursday.

Sixteen people were injured when they were crushed or struck by debris, three of them critically.

“I lost the lottery but this is a winning ticket,” Choo said, holding it in his hand.

Victims ranged from 16 to 64, authorities said. A 50-year-old man and two women, ages 57 and 60, were taken to hospitals in critical condition.

Authorities said it was unclear why the walkway collapsed.

Choo said he was at a nearby store when he heard the crash at the busy noon lunch hour and ran back to find a friend trapped in the debris.

“His whole head was split open,” Choo said.

Two patients at Scripps Mercy Hospital had a broken back and a broken leg, respectively, but were expected to survive, trauma unit medical director Dr. Michael J. Sise told the San Diego Union-Tribune.

The covered walkway was across the street from the St. Vincent de Paul Village shelter and was a favorite hangout for homeless people looking for a little shade. Some victims apparently lived at the shelter, which planned group counseling sessions Friday.

“The walls started moving, then the bang. Everything started coming down. Everyone started screaming,” said Abigail Reckermann, 50, who went to the hospital with a swollen ankle.

Father Joe Carroll, president of St. Vincent de Paul Village, said many of the injured had just eaten lunch or were living at the homeless shelter he runs across the street. The shelter had served lunch to about 1,000 people.

Carroll said his staff recognized some of the shelter clients as they sat on a nearby curb with neck braces. Others were bleeding lightly as they waited for an ambulance.

“They either had a meal here or live here and were walking to the trolley,” he said.

The walkway lined a 275-unit, three-story apartment building under construction by Affirmed Housing Group of San Diego for low-income residents. It is scheduled for completion early next year.